2D Highlight Improved – Pixel Perfect

A pixel perfect version of 2D highlight improved which has the same functionality but is snapped to pixels and uses no blur or filtering.

Shader code
// 2D Pixel Art Highlight Shader
// Creates a crisp pixel line of a given size that periodically glides over the sprite.
//
// You must supply the texture_size uniform with the size of the texture in the sprite.
// Use a negative size_effect for flipping the direction.
shader_type canvas_item;

uniform sampler2D vertical_gradient; // Used to set alpha values
uniform sampler2D color_gradient; // Sets the effect color
uniform float size_effect: hint_range(1.0, 10.0, 1.0) = 1.0; // Size of the effect in pixel units
uniform float speed = 1; // Effect speed
uniform float highlight_strength: hint_range(-4.0, 4.0, 0.05) = 0.5; // Strength of the highlight
uniform bool color_mode_toggle = false; // Toggle for color gradient application
uniform bool is_horizontal = false; // Switches effect direction
uniform float pause_duration = 0.5; // Pause duration between cycles
uniform vec2 texture_size = vec2(16, 16); // Texture size in pixels (e.g., vec2(16.0, 16.0) for a 16x16 texture)

void fragment() {
    // Set up base parameters
    vec4 old_color = COLOR;
    float time = TIME * abs(speed); // Absolute time for both positive and negative speeds
    float effect_cycle_duration = 1.0 + pause_duration; // Total time for one cycle and pause
    float mod_time = mod(time, effect_cycle_duration); // Current time within the cycle

    // Handle the pause
    float progress = mod_time / 1.0; // Normalize mod_time for active duration only

    if (mod_time > 1.0) {
        progress = 1.0; // Hold the highlight at the last position during the pause
    }

    // Reverse the direction if speed is negative
    if (speed < 0.0) {
        progress = 1.0 - progress; // Reverse progress when speed is negative
    }

    // Convert the size_effect from pixels to UV space based on the texture size
    float pixel_to_uv = size_effect / ((is_horizontal) ? texture_size.x : texture_size.y);

    // Calculate the current position of the highlight in UV space
    float current_position = mix(0.0, 1.0, progress);

    // Set the lower and upper bounds for the highlight effect
    float effect_lower_bound = current_position - (pixel_to_uv / 2.0);
    float effect_upper_bound = current_position + (pixel_to_uv / 2.0);

    // Snap the UV coordinates to the pixel grid
    vec2 pixel_size_uv = vec2(1.0) / texture_size;
    vec2 snapped_uv = floor(UV / pixel_size_uv) * pixel_size_uv;

    // Get the position of the pixel in the effect (either horizontal or vertical)
    float position_value = (is_horizontal) ? snapped_uv.x : snapped_uv.y;

    // Use step to create crisp boundaries for the effect
    float effect_distance = step(effect_lower_bound, position_value) - step(effect_upper_bound, position_value);

    // Get the position of the pixel within the inner gradient
    float inner_effect_position = step(effect_lower_bound, position_value) * step(position_value, effect_upper_bound);
    vec2 color_position = (color_mode_toggle) ? vec2(UV.x, inner_effect_position) : vec2(progress);

    // Sample the new color from the color gradient
    vec4 new_color = texture(color_gradient, color_position);

    // Sample the vertical gradient and mix it with the new color
    new_color = mix(old_color, new_color, texture(vertical_gradient, vec2(progress)));

    // Apply the highlight effect using the calculated effect_distance
    COLOR.rgb = mix(old_color.rgb, new_color.rgb, vec3(effect_distance * highlight_strength));
}
Tags
2d, animated, animation, highlight, pixel-art, shine, shining, time
The shader code and all code snippets in this post are under CC0 license and can be used freely without the author's permission. Images and videos, and assets depicted in those, do not fall under this license. For more info, see our License terms.

More from kostilus

Flashing Overlay Shader

Edge Detection Shader

2D Highlight Improved

Related shaders

2D Highlight Improved

Pixel perfect dissolving

Perfect Retro Pixel Shader – Godot 4

Subscribe
Notify of
guest

0 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments